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nuckollsr(at)cox.net
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 Posted: Thu Feb 01, 2007 5:42 am Post subject: Sharing ship's COMM antenna with the hand-held |
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At 09:56 PM 1/31/2007 -0500, you wrote:
| Quote: |
1/31/2007
It will cost more and you won't have as much "roll your own satisfaction",
but the IC-ANT-SB from ICOM is another way to skin this cat. See this web page.
http://www.edmo.com/index.php?module=products&func=display&prod_id=19280&cat_id=
This has been mentioned previously on the list. Check with a local
avionics shop to purchase or GOOGLE IC-ANT-SB for a catalog seller.
OC -- The best investment we will ever make is in gathering knowledge.
|
You got that right! I'd forgotten about that product.
Thanks for reminding me.
I wish I knew more about how it works. I'm still a registered
dealer with Edmo from my Micorair adventure of several years
ago. That coupler is $60 dealer net. If anyone would like to
try it, enter an order on my website at:
http://aeroelectric.com/Catalog/AECcatalog.html
Put "ANTENNA SWITCHBOX (IC-ANT-SB)" in the comments box
at the bottom of the page. I'll get you one for costs.
Let's see what this little critter does and how well
it does it. Just the fact that it bears ICOM's label already
bodes well . . . assuming they're still the company I
knew 30 years ago as a supplier of exemplary ham radio
equipment.
Bob . . .
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retasker(at)optonline.net
Guest
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| Posted: Thu Feb 01, 2007 8:07 pm Post subject: Sharing ship's COMM antenna with the hand-held |
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Bob, Now you are confusing us! In one email you say that this method of switching from the internal radio to the handheld is not so good and you are going to take it off your web site and the next email you are saying that the one ICOM has their name on seems a viable option and offer to sell it to anyone who wants one. What gives??? This product does exactly what the one on your web site does!
Confused...
Dick Tasker
Robert L. Nuckolls, III wrote:
| Quote: |
<nuckollsr(at)cox.net>
At 09:56 PM 1/31/2007 -0500, you wrote:
>
>
> 1/31/2007
>
> It will cost more and you won't have as much "roll your own
> satisfaction", but the IC-ANT-SB from ICOM is another way to skin
> this cat. See this web page.
>
> http://www.edmo.com/index.php?module=products&func=display&prod_id=19280&cat_id=
> This has been mentioned previously on the list. Check with a local
> avionics shop to purchase or GOOGLE IC-ANT-SB for a catalog seller.
>
> OC -- The best investment we will ever make is in gathering knowledge.
You got that right! I'd forgotten about that product.
Thanks for reminding me.
I wish I knew more about how it works. I'm still a registered
dealer with Edmo from my Micorair adventure of several years
ago. That coupler is $60 dealer net. If anyone would like to
try it, enter an order on my website at:
http://aeroelectric.com/Catalog/AECcatalog.html
Put "ANTENNA SWITCHBOX (IC-ANT-SB)" in the comments box
at the bottom of the page. I'll get you one for costs.
Let's see what this little critter does and how well
it does it. Just the fact that it bears ICOM's label already
bodes well . . . assuming they're still the company I
knew 30 years ago as a supplier of exemplary ham radio
equipment.
Bob . . .
|
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Please Note:
No trees were destroyed in the sending of this message. We do concede, however,
that a significant number of electrons may have been temporarily inconvenienced.
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jonlaury
Joined: 06 Nov 2006
Posts: 336
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| Posted: Fri Feb 02, 2007 10:14 am Post subject: Sharing ship's COMM antenna with the hand-held |
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Echoing Dick Tasker's comments.
Casting about on the web, came across remarks that the IC-ANT-SB device would significantly degrade performance of COM-1 when the Handheld was not in use, and that the 3.5 mm jack was "crude".
Listers?
[quote][b]
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nuckollsr(at)cox.net
Guest
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| Posted: Sun Feb 04, 2007 8:26 am Post subject: Sharing ship's COMM antenna with the hand-held |
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At 12:09 PM 2/4/2007 +0000, you wrote:
| Quote: |
<trigo(at)mail.telepac.pt>
With so many different opinions about that little ICOM mixer box, and Bob
N.'s new bad opinion about his own box, I am glad to have decided to
install 2 antennas: one in the upper fuselage skin, exclusively dedicated
to my panel mounted COMM, and the other in the belly, exclusively for the
hand held.
And it's not so obvious that my solution is heavier than the
sole-antenna-with-mixer-and-adapters one ... After all, I needed some
weight behind the baggage compartment ...
OK, there's also the aesthetic and aerodynamics issues of two sticks
protruding from the bird ...
|
A dedicated antenna is ALWAYS the simplest, most reliable
means for making sure your hand held is not crippled along
with the panel mount because something common to both radios
in the antenna system came unhooked. This scenario is exceedingly
unlikely . . . after all, how many parts are shared and how
vulnerable are they to failure?
I'm not sure I've read a cogent opinion about the
ICOM box yet. One individual opined as to the choice of
connectors but offered nothing about real performance
losses or longevity in the a/c.
The jury is still out on this folks . . . and even
if we do craft something perceived to be a cut above
the present technologies, that doesn't necessarily make
the current offerings "bad" . . . they're simply
candidates for improvement. If someone could identify
a 3.5mm jack that's more robust than the Radio Shack part
I used in the original article, that would be an attractive
step up. I've got some ICOM boxes coming. Let's tear one open
and see what they look like.
Bob . . .
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john(at)ballofshame.com
Guest
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| Posted: Sun Feb 04, 2007 8:53 am Post subject: Sharing ship's COMM antenna with the hand-held |
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Has anyone taken a radio, say an SL-30, and measured the resistance of
the antenna input when the radio is off? If it's anywhere near 50 ohms,
this problem is trivial to solve with a T coax fitting and a 50 ohm
terminator.
-John
www.ballofshame.com
Robert L. Nuckolls, III wrote:
| Quote: |
<nuckollsr(at)cox.net>
At 12:09 PM 2/4/2007 +0000, you wrote:
>
> <trigo(at)mail.telepac.pt>
>
> With so many different opinions about that little ICOM mixer box, and
> Bob N.'s new bad opinion about his own box, I am glad to have decided
> to install 2 antennas: one in the upper fuselage skin, exclusively
> dedicated to my panel mounted COMM, and the other in the belly,
> exclusively for the hand held.
> And it's not so obvious that my solution is heavier than the
> sole-antenna-with-mixer-and-adapters one ... After all, I needed some
> weight behind the baggage compartment ...
> OK, there's also the aesthetic and aerodynamics issues of two sticks
> protruding from the bird ...
A dedicated antenna is ALWAYS the simplest, most reliable
means for making sure your hand held is not crippled along
with the panel mount because something common to both radios
in the antenna system came unhooked. This scenario is exceedingly
unlikely . . . after all, how many parts are shared and how
vulnerable are they to failure?
I'm not sure I've read a cogent opinion about the
ICOM box yet. One individual opined as to the choice of
connectors but offered nothing about real performance
losses or longevity in the a/c.
The jury is still out on this folks . . . and even
if we do craft something perceived to be a cut above
the present technologies, that doesn't necessarily make
the current offerings "bad" . . . they're simply
candidates for improvement. If someone could identify
a 3.5mm jack that's more robust than the Radio Shack part
I used in the original article, that would be an attractive
step up. I've got some ICOM boxes coming. Let's tear one open
and see what they look like.
Bob . . .
|
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N1DeltaWhiskey(at)comcast
Guest
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| Posted: Sun Feb 04, 2007 10:00 am Post subject: Sharing ship's COMM antenna with the hand-held |
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John,
Not sure what you are getting at here, but simply measuring the in
"resistance" of the antenna input will, I think, tell you little. Or, maybe
I am missing what you are suggesting.
Did a quick look at "characteristic impedance" on Wikipedia. When one talks
about transmission cables (and matching connections), impedance is the
"apparent resistance" to AC signals that the line is rated in, not simple
resistance. I believe you are talking about measuring the impedance, not
solely the resistance, of the input.
I could surmise some thing about this, but probably make myself look a
little (maybe a lot) unknowledgeable, so will leave further clarification to
those with a better understanding of the subject. But a good starting place
for discussion is to have an understanding of the relevant terms
Regards,
Doug Windhorn.
---
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john(at)ballofshame.com
Guest
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| Posted: Sun Feb 04, 2007 10:20 am Post subject: Sharing ship's COMM antenna with the hand-held |
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If you short a 50 ohm resistor across the end of a 50 ohm coax, you will
effectively remove that "leg" of the cable from the circuit so far as
back reflection is concerned. This is called terminating. Basically,
the 50ohm resistor acts the same as an infinitely long coax, if that
makes sense?
So if radio manufacturers where clever, they would setup their antenna
inputs to short across a 50ohm load when the unit is off, effectively
terminating their end of the cable. On the panel, you use a T with a 50
ohm terminator in the panel side. If you need to use a handheld, you
can turn off the panel mount and replace the 50 ohm terminator with your
handheld input. The downside is that you will loose range.
Don't take any of this as a suggestion. It was just something that
flashed into my brain this morning when I thought about how to make
every compatible. I think this would work but you'd sacrifice
performance, so it's probably not viable.
-John
Doug Windhorn wrote:
[quote]
<N1DeltaWhiskey(at)comcast.net>
John,
Not sure what you are getting at here, but simply measuring the in
"resistance" of the antenna input will, I think, tell you little. Or,
maybe I am missing what you are suggesting.
Did a quick look at "characteristic impedance" on Wikipedia. When one
talks about transmission cables (and matching connections), impedance
is the "apparent resistance" to AC signals that the line is rated in,
not simple resistance. I believe you are talking about measuring the
impedance, not solely the resistance, of the input.
I could surmise some thing about this, but probably make myself look a
little (maybe a lot) unknowledgeable, so will leave further
clarification to those with a better understanding of the subject.
But a good starting place for discussion is to have an understanding
of the relevant terms
Regards,
Doug Windhorn.
---
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nuckollsr(at)cox.net
Guest
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| Posted: Sun Feb 04, 2007 10:23 am Post subject: Sharing ship's COMM antenna with the hand-held |
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At 10:04 AM 2/4/2007 -0500, you wrote:
| Quote: | In a message dated 2/4/2007 6:16:28 A.M. Central Standard Time,
trigo(at)mail.telepac.pt writes:
With so many different opinions about that little ICOM mixer box, and Bob
N.'s new bad opinion about his own box, I am glad to have decided to install
2 antennas: one in the upper fuselage skin, exclusively dedicated to my
panel mounted COMM, and the other in the belly, exclusively for the hand
held.
And it's not so obvious that my solution is heavier than the
sole-antenna-with-mixer-and-adapters one ... After all, I needed some weight
behind the baggage compartment ...
OK, there's also the aesthetic and aerodynamics issues of two sticks
protruding from the bird ...
Carlos
RV-9A, still wiring
Good Morning Carlos,
Many years ago in a land far, far away, I was a fairly active participant
in the competitive glider flying scene.
Many of my friends used a hole in the belly through which they shoved an
antenna when they wanted to use their radio. I tried it a few times and it
seemed to work OK. For competitive flying, the hole was covered with a
hunk of two hundred mile per hour white racing tape (otherwise known as 3M
electrical tape.)
|
Hmmmm . . . don't know if I dare admit this but for
a time I had a "portable antenna" that could be taped
to the strut of a high wing airplane, coax routed down
the strut and through the lower aft corner of one of
those cabin doors that never did shut tight. . . . or
through a fresh air scoop that didn't feature screened
ducts.
It offered a quantum jump in performance for the little
1 watt hand-held and it's performance-limited rubber duck
antenna.
Bob . . .
----------------------------------------
( IF one aspires to be "world class", )
( what ever you do must be exercised )
( EVERY day . . . )
( R. L. Nuckolls III )
----------------------------------------
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bobf(at)feldtman.com
Guest
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| Posted: Mon Feb 05, 2007 7:52 pm Post subject: Sharing ship's COMM antenna with the hand-held |
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I gotta respond finally - resistance has nothing to do with impedance.
To try to measure the "resistance" of the output circuit might give you
anything from a dead short to infinity! Depends on the output
circuit.... Invest in a copy of the ARRL antenna handbook (www.arrl.org)
and learn about antennas the right way - the way we hams do.... Like
OBAM guys built and fly airplanes, amateurs build and test radios and
antennas. You'll learn all about duplexers, dipoles, etc.
bobf
(Glastar) and W5RF amateur extra class.
John Coloccia wrote:
| Quote: |
<john(at)ballofshame.com>
Has anyone taken a radio, say an SL-30, and measured the resistance of
the antenna input when the radio is off? If it's anywhere near 50
ohms, this problem is trivial to solve with a T coax fitting and a 50
ohm terminator.
-John
www.ballofshame.com
Robert L. Nuckolls, III wrote:
>
> <nuckollsr(at)cox.net>
>
> At 12:09 PM 2/4/2007 +0000, you wrote:
>
>>
>> <trigo(at)mail.telepac.pt>
>>
>> With so many different opinions about that little ICOM mixer box,
>> and Bob N.'s new bad opinion about his own box, I am glad to have
>> decided to install 2 antennas: one in the upper fuselage skin,
>> exclusively dedicated to my panel mounted COMM, and the other in the
>> belly, exclusively for the hand held.
>> And it's not so obvious that my solution is heavier than the
>> sole-antenna-with-mixer-and-adapters one ... After all, I needed
>> some weight behind the baggage compartment ...
>> OK, there's also the aesthetic and aerodynamics issues of two sticks
>> protruding from the bird ...
>
> A dedicated antenna is ALWAYS the simplest, most reliable
> means for making sure your hand held is not crippled along
> with the panel mount because something common to both radios
> in the antenna system came unhooked. This scenario is exceedingly
> unlikely . . . after all, how many parts are shared and how
> vulnerable are they to failure?
>
> I'm not sure I've read a cogent opinion about the
> ICOM box yet. One individual opined as to the choice of
> connectors but offered nothing about real performance
> losses or longevity in the a/c.
>
> The jury is still out on this folks . . . and even
> if we do craft something perceived to be a cut above
> the present technologies, that doesn't necessarily make
> the current offerings "bad" . . . they're simply
> candidates for improvement. If someone could identify
> a 3.5mm jack that's more robust than the Radio Shack part
> I used in the original article, that would be an attractive
> step up. I've got some ICOM boxes coming. Let's tear one open
> and see what they look like.
>
> Bob . . .
>
|
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